fix dex/kubernetes link

Author: mkontani

content/en/docs/reference/access-authn-authz/authentication.md

@@ -345,7 +345,7 @@ Or you can use [this similar script](https://raw.githubusercontent.com/TremoloSe
 Setup instructions for specific systems:
 
 - [UAA](https://docs.cloudfoundry.org/concepts/architecture/uaa.html)
-- [Dex](https://github.com/dexidp/dex/blob/master/Documentation/kubernetes.md)
+- [Dex](https://dexidp.io/docs/kubernetes/)
 - [OpenUnison](https://www.tremolosecurity.com/orchestra-k8s/)
 
 #### Using kubectl

content/ja/docs/reference/access-authn-authz/authentication.md

@@ -258,7 +258,7 @@ IDプロバイダーがKubernetesと連携するためには、以下のこと
 特定のシステム用のセットアップ手順は、以下を参照してください。
 
 - [UAA](https://docs.cloudfoundry.org/concepts/architecture/uaa.html)
-- [Dex](https://github.com/dexidp/dex/blob/master/Documentation/kubernetes.md)
+- [Dex](https://dexidp.io/docs/kubernetes/)
 - [OpenUnison](https://www.tremolosecurity.com/orchestra-k8s/)
 
 #### kubectlの使用

content/zh/docs/reference/access-authn-authz/authentication.md

@@ -700,7 +700,7 @@ Setup instructions for specific systems:
 特定系统的安装指令：
 
 - [UAA](https://docs.cloudfoundry.org/concepts/architecture/uaa.html)
-- [Dex](https://github.com/dexidp/dex/blob/master/Documentation/kubernetes.md)
+- [Dex](https://dexidp.io/docs/kubernetes/)
 - [OpenUnison](https://www.tremolosecurity.com/orchestra-k8s/)
 
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